Many liquid crystal display devices as flat panel display devices are provided with sandwich structures of electronic circuit array substrates, counter substrates and liquid crystal compositions as shown in Japanese Patent Publication 2000-187248 (particularly, see descriptions at pages 4–6 and FIGS. 1–3), for instance. The electronic circuit array substrates include insulation substrates such as glass plates on which pixels are configured in a matrix form. Each pixel contains a set of red, green and blue color-display dots, for instance, each of which includes a pixel electrode, an electric capacitor and thin-film transistors.
Further, island-like poly-crystalline silicon films, for instance, are formed on the electronic circuit array substrate. The silicon films are covered with a gate insulation film on which, in turn, scanning lines connected to gate electrodes disposed. Auxiliary electric capacitor lines are provided apart from the scanning lines but on the gate insulation film.
The scanning lines and the auxiliary electric capacitor lines are coated with an interlayer insulation film through which contact holes are made. Signal lines are formed on the interlayer film and are electrically connected to the poly-crystalline silicon layer through the contact holes in which electrically conductive materials are filled.
The array substrate is provided opposite to the counter substrate which includes an insulation substrate such as a glass substrate and color filters formed on the insulation substrate. A liquid crystal composition is held between the electronic circuit array and counter substrates and is sealed at circumferences of the substrates by a sealant.
The liquid crystal display device described above needs a large number of pixels to display a mass of data. A color liquid crystal display device of this type, in particular, used for a personal computer requires red, green and blue color-display dots per pixel so that its electronic circuit array substrate must be provided with several millions of pixels with them
Display requirements for such a liquid crystal display device have been recently quite high in level. One such requirement is to have as little point-defect pixels as possible or no point-defect pixels. It is, however, extremely difficult to manufacture liquid crystal display devices with little or no point-defect pixels at a good yield rate. Thus, it is important to provide a liquid crystal display device with no point-defect pixel structures or methods of manufacturing the same.
One of the big causes of point-defect pixels is electro-static destruction in manufacturing an electronic circuit array substrate of a liquid crystal display device. Abnormal characteristics of the thin-film transistors, for instance, may be caused by electro-static destructions in the case that an electronic circuit array substrate is washed after the formation of poly-crystalline silicon films patterned for thin-film transistors, a gate insulation film, scanning lines, auxiliary capacitor lines, an interlayer insulation film and contact holes in the interlayer and gate insulation films on the electronic circuit array substrate, i.e., before the formation of signal lines on the interlayer insulation film.